Prior to the anime series, En and his sister, Princess Amano, are grown up in their home planet, until Zan destroys it and later attacks their spaceship (Needle Tower), which results her being in paralysis. She was put into cryogenic sleep in her paralysis state inside the capsule for the next several years while wielding her sword, and her brother En becomes the G.C. of Primas before he passes his license to Baku in the first episode. In the anime her name is never mentioned. (Source: Hero Wikia, edited)